The present invention generally concerns diamond film structures, and more specifically concerns articles particularly configured for conducting, generating, absorbing and/or measuring the flow of thermal energy. Also disclosed are methods of forming same.
Diamond films have a very high thermal conductivity and stability, a large band gap, and excellent chemical/radiation resistance, thus making the diamond films useful in high temperature and/or chemically active and radiation active environments. Still further, pure diamond films are normally electrically insulative, but can be made electrically conductive by doping, thus making them useful in the electronic industry. With the advent of recent advances in chemical vapor deposition (CVD) processes, diamond films can now be grown on non-diamond substrates in high volume and in a cost effective manner. However, diamond film structures taking full advantage of these properties have not yet been developed.
For example, most currently available heater structures use a metal heater element embedded in an insulator. To monitor the temperature, thermocouples or temperature sensors are used. One kind uses platinum elements insulated by Kapton or by silicone rubber. However, the maximum attainable heater temperature is approximately 200.degree. C. Further, the thickness of the heater is several thousandths of an inch. If temperature sensors are imbedded in the heaters, the thickness is increased and there are more layers joined by adhesives. The result of using these layers is increased thermal resistance and significant temperature drop inside the heater itself. Another kind of heater uses mica sheets to allow the reaching of about 600.degree. C., maximum. However, this results in even thicker heaters, approximately 0.040 inches in thickness. Furthermore, the surfaces of the mica are not flat, since the outline of the heater elements is impressed on the surface. Also, the temperature drop in the mica is even greater than in the heaters mentioned above. Some silicon nitride coated heaters are used for temperatures in excess of 1000.degree. C. However, integration of a sensor with the heater, poor thermal conductivity of electrical insulators, thermal mismatch between the heater element and the insulator coating, and poor thermal contact to the sample to be heated are some of the continuing major problems of present heater technology.
In another example, commercially available diamond heat sinks are typically attached to micro chips and integrated circuits by adhesive, such as thermal epoxies. However, as with heaters, the adhesive decreases the effectiveness of the adhered heat sinks. Thus, it is desirable to have Si/diamond or GaAs/diamond wafers, i.e., wafers with built-in diamond heats sinks.
Thus, diamond film structures solving the aforementioned problems are desired.